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Richard A F Clark - One of the best experts on this subject based on the ideXlab platform.
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fibrin and wound healing
Annals of the New York Academy of Sciences, 2006Co-Authors: Richard A F ClarkAbstract:Although hemostasis is the major role of fibrin in wound repair, once the clot is present the wound cells must deal with it. The invasion and clearing of fibrin by these cells involves multiple complex processes that may go array XXX and delay wound repair. A good example, of the latter is leg ulcers. These chronic wounds contain a plethora of proteases that digest fibronectin and growth factors in the fibrin clot resulting in a corrupt Provisional Matrix that no longer supports reepithelialization or granulation tissue formation. Every good wound care provider knows that these wounds will not heal unless the corrupt Matrix is removed by vigorous debridement that stimulates the accumulation of a competent Provisional Matrix.
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Potential Functions of the Clotting System in Wound Repair
The Molecular and Cellular Biology of Wound Repair, 1998Co-Authors: Harold F Dvorak, Allen P. Kaplan, Richard A F ClarkAbstract:Injuries of many types and degrees, ranging from inflammation to frank blood vessel disruption, lead to plasma extravasation and extravascular fibrin clot formation. The clot is composed of crosslinked fibrin and fibronectin and platelets that together entrap plasma water, plasma proteins, and blood cells, primarily erythrocytes. This fibrin gel Matrix not only halts bleeding but also establishes a Provisional Matrix for the influx of inflammatory cells and par-enchymal cells into the injured tissue. With time, this surface clot dessicates to form the familiar scab, which in turn sloughs as wound healing proceeds from below.
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fibronectin provides a conduit for fibroblast transmigration from collagenous stroma into fibrin clot Provisional Matrix
Journal of Cell Science, 1997Co-Authors: Doris Greiling, Richard A F ClarkAbstract:After injury, the wound space is filled with a fibrin/fibronectin clot containing growth factors released by platelets and monocytes. In response to these factors, fibroblasts migrate into the fibrin clot and contribute to the formation of granulation tissue. The functional mechanisms allowing fibroblasts to leave the collagenous Matrix of normal connective tissue and invade the Provisional Matrix of the fibrin clot have not been fully defined. To investigate these mechanisms we established a new in vitro model which simulates specific aspects of early wound healing, that is, the migration of fibroblasts from a three-dimensional collagen Matrix into a fibrin clot. This transmigration could be induced by physiological concentrations of platelet releasate or platelet-derived growth factor BB (PDGF-BB) in a concentration-dependent manner. At 24 hours irradiated fibroblasts invaded the fibrin gel almost as well as non-irradiated cells, indicating that transmigration was independent of proliferation. Plasminogen and its activators appear to be necessary for invasion of the fibrin clot since protease inhibitors decreased the amount of migration. These serine proteases, however, were not necessary for exit from the collagen gel as fibroblasts migrated out of the collagen gel onto a surface coated with fibrin fibrils even in the presence of inhibitors. Removal of fibronectin (FN) from either the collagen gel or the fibrin gel markedly decreased the number of migrating cells, suggesting that FN provides a conduit for transmigration. Cell movement in the in vitro model was inhibited by RGD peptide, and by monoclonal antibodies against the subunits of the alpha5 beta1 and alpha v beta3 integrin receptor. Thus, the functional requirements for fibroblast transmigration from collagen-rich to fibrin-rich matrices, such as occurs in early wound healing, have been partially defined using an in vitro paradigm of this important biologic process.
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Studies in Vitro on the Role of αv and β1 Integrins in the Adhesion of Human Dermal Fibroblasts to Provisional Matrix Proteins Fibronectin, Vitronectin, and Fibrinogen
The Journal of investigative dermatology, 1996Co-Authors: James Gailit, Richard A F ClarkAbstract:Fibroblasts that migrate into a wound during the early stages of repair use cell surface integrins to interact with extracellular molecules as they move away from the interstitial Matrix of normal tissue and into the Provisional Matrix of the wound. Therefore, to understand a critical phase of wound healing, it is necessary to understand the details of integrin involvement. Normal adult human dermal fibroblasts in culture express many receptors for the Provisional Matrix proteins fibronectin, vitronectin, and fibrinogen, including the integrins α 3 β 1, α 4 β 1, α 5 β 1, α v β 1, α v β 3, and α v β 5. We used quantitative flow cytometry to estimate the relative numbers of these receptors and immunoprecipitation to confirm the expression of α v β 1. Adult human dermal fibroblasts primarily use β 1 integrins, α 4 β 1, α 5 β 1, and possibly α v β 1, for attachment to fibronectin. α v β 3 and perhaps other integrins containing the α v subunit serve fibroblasts as secondary or auxiliary receptors for fibronectin. In contrast, these cells use α v integrins but probably not β 1 integrins for attachment to vitronectin. α v β 3 and α v β 5 apparently act in concert to mediate attachment to vitronectin, and these two integrins may perform different functions during wound repair. Fibroblast adhesion to certain preparations of fibrinogen occurs, at least partially, through the small amount of fibronectin present in the preparations. Fibroblast attachment to fibrinogen purified free of fibronectin also occurs, and that was demonstrated with a sensitive new assay called electrical cell-substrate impedance sensing. Fibroblast attachment to pure fibrinogen can be inhibited by RGD peptide, suggesting that integrins are involved.
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Extracellular Matrix alters PDGF regulation of fibroblast integrins.
Journal of Cell Biology, 1996Co-Authors: Richard A F ClarkAbstract:Extracellular Matrix (ECM) and growth factors are potent regulators of cell phenotype. These biological mediators of cellular responses are potentially interactive and as such could drive cells through progressive phenotypes to create new tissue as in morphogenesis and wound repair. In fact, ECM composition changes during tissue formation accompanied by alterations in cell growth and migration. How alterations in the ECM regulate cell activities is poorly defined. To address this question in wound repair, we cultured normal human dermal skin fibroblasts in relaxed collagen gels, fibronectin-rich cultures or stressed fibrin gels, and stressed collagen gels to model normal dermis, early wound Provisional Matrix, and late granulation tissue, respectively. Integrin subunits, alpha 2, alpha 3, and alpha 5, that define receptor specificity for collagen and Provisional Matrix, respectively, were measured at mRNA steady-state level before and after stimulation with platelet-derived growth factor-BB (PDGF-BB), a potent mitogen and chemoattractant for fibroblasts. Fibronectin-rich cultures and fibrin gels supported PDGF-BB induction of alpha 3 and alpha 5 mRNA. In contrast, both stressed and relaxed collagen attenuated these responses while promoting maximal alpha 2 mRNA expression. Posttranscriptional regulation was an important mechanism in this differential response. Together PDGF-BB and collagen gels promoted alpha 2, but not alpha 3 and alpha 5, mRNA stability. Conversely, when fibroblasts were in fibronectin-rich cultures, PDGF-BB promoted alpha 3 and alpha 5, but not alpha 2, mRNA stability. We suggest that ECM alterations during wound healing or any new tissue formation cause cells to respond differently to repeated growth factor stimuli. An ordered progression of cell phenotypes results, ultimately consummating tissue repair or morphogenesis.
Jean E Schwarzbauer - One of the best experts on this subject based on the ideXlab platform.
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Adenoviral-mediated expression and local deposition of recombinant tenascin-C perturbs cell-dependent Matrix contraction.
The Journal of surgical research, 2006Co-Authors: Henry C Hsia, Jean E SchwarzbauerAbstract:Background To mimic the wound environment, we have developed a three-dimensional (3-D) fibrin-fibronectin (FN) Matrix model that is formed in vitro from purified proteins and approximates the Provisional Matrix. Tenascin-C, a large extracellular Matrix (ECM) glycoprotein, is expressed transiently in tissue adjacent to areas of injury and contacts the Provisional Matrix in vivo . We have constructed a novel recombinant adenovirus vector (Ad-70Ten) to up-regulate local expression and secretion of a recombinant form of tenascin-C. Methods Ad-70Ten and a control vector were constructed and used to infect cultured mammalian cells. Post-infection monitoring of expression was accomplished by immunoblot and immunohistochemical techniques. Local protein deposition was examined by immunofluorescence. Cell contractility was assessed by ability of infected cells to contract 3-D fibrin-FN matrices. Some matrices also contained lysophosphatidic acid (LPA), an activator of Rho GTPase. Results Adenovirus-infected cells demonstrated high recombinant tenascin-C expression and deposited protein at sites of cell-Matrix contacts resulting in significantly reduced contractility with 2.5-fold lower contraction of the Matrix compared with control cells. Matrix contraction could be restored by treatment with LPA. Conclusion These results show that endogenous expression of tenascin-C down-regulates cell contractility and strongly suggest that it exerts its effects via a Rho GTPase signaling pathway. Taken with previous findings, these results suggest that tenascin-C acts in both a paracrine and autocrine manner via Rho GTPase pathways. This report demonstrates that recombinant adenovirus infection is a feasible method to induce high expression of large Matrix proteins in mammalian cells, allowing better approximation of in vivo circumstances for investigations of locally secreted Matrix protein. While the current vector has been constructed for research purposes, it also represents a proof in principle that adenoviral vectors encoding large proteins may have potential benefit in clinical applications.
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fibronectin fragmentation promotes α4β1 integrin mediated contraction of a fibrin fibronectin Provisional Matrix
Experimental Cell Research, 2005Co-Authors: Leyla V Valenick, Henry C Hsia, Jean E SchwarzbauerAbstract:Abstract In injured tissues, the fibrin–fibronectin (FN) Provisional Matrix provides a framework for cell adhesion, migration, and repair. Effective repair and remodeling require a proper balance between extracellular Matrix (ECM) deposition, contraction, and turnover. We utilized a three-dimensional (3D) fibrin–FN Provisional Matrix model to determine the contributions of the FN-binding integrin receptors α5β1 and α4β1 to Matrix contraction. CHOα5 cells expressing α5β1, a receptor for FN's RGD cell-binding domain, were highly contractile, and cells were well spread on a 3D fibrin–FN Matrix. In contrast, CHOα4 cells expressing the α4β1 receptor for FN's alternatively spliced V region attached less efficiently to FN and were deficient in fibrin–FN Matrix contraction. Surprisingly, cell adhesion and Matrix contraction by CHOα4 cells were dramatically enhanced, to levels equivalent to CHOα5 cells, when proteolyzed FN was used in place of intact FN in the fibrin–FN Matrix. Similar enhancement was observed when ligand binding by α4β1 integrins was activated by treatment with Mn ++ , but not by stimulation of actin organization with LPA. Therefore, α4β1-dependent cell responses to the Provisional Matrix are modulated by cleavage of Matrix components.
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Fibronectin fragmentation promotes α4β1 integrin-mediated contraction of a fibrin-fibronectin Provisional Matrix
Experimental cell research, 2005Co-Authors: Leyla V Valenick, Henry C Hsia, Jean E SchwarzbauerAbstract:Abstract In injured tissues, the fibrin–fibronectin (FN) Provisional Matrix provides a framework for cell adhesion, migration, and repair. Effective repair and remodeling require a proper balance between extracellular Matrix (ECM) deposition, contraction, and turnover. We utilized a three-dimensional (3D) fibrin–FN Provisional Matrix model to determine the contributions of the FN-binding integrin receptors α5β1 and α4β1 to Matrix contraction. CHOα5 cells expressing α5β1, a receptor for FN's RGD cell-binding domain, were highly contractile, and cells were well spread on a 3D fibrin–FN Matrix. In contrast, CHOα4 cells expressing the α4β1 receptor for FN's alternatively spliced V region attached less efficiently to FN and were deficient in fibrin–FN Matrix contraction. Surprisingly, cell adhesion and Matrix contraction by CHOα4 cells were dramatically enhanced, to levels equivalent to CHOα5 cells, when proteolyzed FN was used in place of intact FN in the fibrin–FN Matrix. Similar enhancement was observed when ligand binding by α4β1 integrins was activated by treatment with Mn ++ , but not by stimulation of actin organization with LPA. Therefore, α4β1-dependent cell responses to the Provisional Matrix are modulated by cleavage of Matrix components.
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coregulation of fibronectin signaling and Matrix contraction by tenascin c and syndecan 4
Molecular Biology of the Cell, 2004Co-Authors: Kim S Midwood, Leyla V Valenick, Henry C Hsia, Jean E SchwarzbauerAbstract:Syndecan-4 is a ubiquitously expressed heparan sulfate proteoglycan that modulates cell interactions with the extracellular Matrix. It is transiently up-regulated during tissue repair by cells that mediate wound healing. Here, we report that syndecan-4 is essential for optimal fibroblast response to the three-dimensional fibrin-fibronectin Provisional Matrix that is deposited upon tissue injury. Interference with syndecan-4 function inhibits Matrix contraction by preventing cell spreading, actin stress fiber formation, and activation of focal adhesion kinase and RhoA mediated-intracellular signaling pathways. Tenascin-C is an extracellular Matrix protein that regulates cell response to fibronectin within the Provisional Matrix. Syndecan-4 is also required for tenascin-C action. Inhibition of syndecan-4 function suppresses tenascin-C activity and overexpression of syndecan-4 circumvents the effects of tenascin-C. In this way, tenascin-C and syndecan-4 work together to control fibroblast morphology and signaling and regulate events such as Matrix contraction that are essential for efficient tissue repair.
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tenascin c modulates Matrix contraction via focal adhesion kinase and rho mediated signaling pathways
Molecular Biology of the Cell, 2002Co-Authors: Kim S Midwood, Jean E SchwarzbauerAbstract:A Provisional Matrix consisting of fibrin and fibronectin (FN) is deposited at sites of tissue damage and repair. This Matrix serves as a scaffold for fibroblast migration into the wound where these cells deposit new Matrix to replace lost or damaged tissue and eventually contract the Matrix to bring the margins of the wound together. Tenascin-C is expressed transiently during wound repair in tissue adjacent to areas of injury and contacts the Provisional Matrix in vivo. Using a synthetic model of the Provisional Matrix, we have found that tenascin-C regulates cell responses to a fibrin-FN Matrix through modulation of focal adhesion kinase (FAK) and RhoA activation. Cells on fibrin-FN+tenascin-C redistribute their actin to the cell cortex, downregulate focal adhesion formation, and do not assemble a FN Matrix. Cells surrounded by a fibrin-FN+tenascin-C Matrix are unable to induce Matrix contraction. The inhibitory effect of tenascin-C is circumvented by downstream activation of RhoA. FAK is also required for Matrix contraction and the absence of FAK cannot be overcome by activation of RhoA. These observations show dual requirements for both FAK and RhoA activities during contraction of a fibrin-FN Matrix. The effects of tenascin-C combined with its location around the wound bed suggest that this protein regulates fundamental processes of tissue repair by limiting the extent of Matrix deposition and contraction to fibrin-FN-rich Matrix in the primary wound area.
Daria A. Narmoneva - One of the best experts on this subject based on the ideXlab platform.
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tissue engineered Provisional Matrix as a novel approach to enhance diabetic wound healing
Wound Repair and Regeneration, 2012Co-Authors: Swathi Balaji, Sachin S. Vaikunth, Stephanie Lang, Abdul Q. Sheikh, Foong Y. Lim, Timothy M. Crombleholme, Daria A. NarmonevaAbstract:Inherent pathologies associated with diabetic wound microenvironment including increased proteolysis, inflammatory dysregulation, and impaired neovascularization prevent timely resolution of chronic diabetic ulcers. It is hypothesized that augmentation of local wound microenvironment with a stable Provisional Matrix formed by proteolysis-resistant angiogenic peptide nanofibers (NFs) will create permissive environment for attenuated inflammation, enhanced neovascularization, and improved diabetic wound healing. Using murine excisional wound healing models, full-thickness dorsal skin wounds were treated with either NFs or control solutions (phosphate buffered saline; hyaluronic acid) and analyzed for morphology, inflammatory response, neovascularization, and biomechanical properties. NF treatment of diabetic wounds stimulated formation of a robust pro-angiogenic in situ tissue-engineered Provisional Matrix leading to a significant decrease in wound inflammatory cell infiltration and proinflammatory interleukin-6 levels, a significant increase in endothelial and endothelial progenitor cell infiltration, vascular endothelial growth factor levels, and neovascularization (day 7), as well as improved wound morphology, accelerated wound closure, and significantly stronger repair tissue (day 28). These results suggest that appropriate design of Provisional Matrix may compensate for some of the complex disruptions in diabetic wound microenvironment and provide missing cues to cells and direct in situ responses toward improved healing, which is promising for future development of new therapies for diabetic ulcers.
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Tissue‐engineered Provisional Matrix as a novel approach to enhance diabetic wound healing
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, 2011Co-Authors: Swathi Balaji, Sachin S. Vaikunth, Stephanie Lang, Abdul Q. Sheikh, Foong Y. Lim, Timothy M. Crombleholme, Daria A. NarmonevaAbstract:Inherent pathologies associated with diabetic wound microenvironment including increased proteolysis, inflammatory dysregulation, and impaired neovascularization prevent timely resolution of chronic diabetic ulcers. It is hypothesized that augmentation of local wound microenvironment with a stable Provisional Matrix formed by proteolysis-resistant angiogenic peptide nanofibers (NFs) will create permissive environment for attenuated inflammation, enhanced neovascularization, and improved diabetic wound healing. Using murine excisional wound healing models, full-thickness dorsal skin wounds were treated with either NFs or control solutions (phosphate buffered saline; hyaluronic acid) and analyzed for morphology, inflammatory response, neovascularization, and biomechanical properties. NF treatment of diabetic wounds stimulated formation of a robust pro-angiogenic in situ tissue-engineered Provisional Matrix leading to a significant decrease in wound inflammatory cell infiltration and proinflammatory interleukin-6 levels, a significant increase in endothelial and endothelial progenitor cell infiltration, vascular endothelial growth factor levels, and neovascularization (day 7), as well as improved wound morphology, accelerated wound closure, and significantly stronger repair tissue (day 28). These results suggest that appropriate design of Provisional Matrix may compensate for some of the complex disruptions in diabetic wound microenvironment and provide missing cues to cells and direct in situ responses toward improved healing, which is promising for future development of new therapies for diabetic ulcers.
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Angiogenic Nanoscaffold Accelerates Diabetic Wound Healing and Improves Wound Tissue Strength in db/db Mice
ASME 2009 Summer Bioengineering Conference Parts A and B, 2009Co-Authors: Swathi Balaji, Abdul Q. Sheikh, Foong Y. Lim, Timothy M. Crombleholme, Lee M. Morris, Daria A. NarmonevaAbstract:Chronic ulcers are a leading cause of morbidity in diabetic patients. Diabetes is associated with major changes in the wound microenvironment and disruption of normal wound healing process, characterized by a prolonged inflammatory phase with elevated levels of wound proteases and increased degradation of extracellular Matrix (ECM) components [1]. This impedes wound healing due to a lack of Provisional Matrix, impaired recruitment and survival of endothelial (EC) and endothelial precursor (EPC) cells, and insufficient neovascularization, resulting in delayed healing. Therefore, strategies focused on restoring the diabetic wound microenvironment by decreasing ECM degradation and promoting neovascularization are promising for development of new therapies to treat chronic diabetic ulcers.Copyright © 2009 by ASME
Katja Nelson - One of the best experts on this subject based on the ideXlab platform.
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Bone physiology in human grafted and non-grafted extraction sockets--an immunohistochemical study.
Clinical oral implants research, 2012Co-Authors: Susanne Nahles, Hermann Lage, John J. Nelson, Claudia Nack, Kerrin Gratecap, Katja NelsonAbstract:Purpose The aim of the present immunohistological investigation was to define and compare the osteogenic potential with the vascularization of the Provisional Matrix in grafted and ungrafted extraction sockets after 4 and 12 weeks of healing. Methods A total of 33 Patients (15 women, 18 men) with 65 extraction sites with a mean age of 54.4 years (30–73 years) participated in this study. After tooth extraction, the sockets were augmented with Bio-Oss collagen or non-augmented. At implant placement after 4 or 12 weeks bone biopsies were obtained. Within the specimens the osteogenic and endothelial potential of mesenchymal cells was analyzed in the Provisional Matrix using immunohistochemical analysis with three monoclonal antibodies Cbfa1/Runx2, Osteocalcin (OC), and CD31. Statistical analysis was performed using Mann–Whitney U-test, Spearman's rank-order correlation coefficient, and the two-factorial analysis for repeated measurements. Results Of the 65 extraction sockets, 25 (13 non-augmented, 12 augmented) sites after 4 weeks healing time and 40 (19 non-augmented, 21 augmented) sites after 12 weeks healing time were involved in the study. No signs of acute or chronic inflammation were noted in any specimens. After 4 weeks, a median amount of 56% (10–85%) of Cbfa1 positive cells and a median amount of cells expressing OC of 21% (5–42%) were measured. A median CD31 score of 5 was observed. After 12 weeks, a median amount of 61% (19–90%) positive cells expressed by Cbfa1/Runx2 staining a median amount of OC positive cells of 9% (2–17%) was measured. The results at 12 weeks revealed a median score of CD31 positive cells of 3. Discussion Osteoblastic activity in the Provisional Matrix was highest after 4 weeks of healing period. The active zone of bone formation is found in the apical region of the extraction socket during the early healing phase, shifting to the coronal region after 12 weeks. A peak of osteoblast activity within the first weeks is followed by a reduction in mature osteoblasts with osteoblasts remaining in an inactive stage. The vascularity changed in likewise fashion to the maturation of osteoblasts within the observation period. The results have shown that with increasing age a decreasing endothelial potential was observed not after 4 weeks, but after 12 weeks, thus it suggests that angiogenesis is diminished in older patients in the later phase of healing in extraction sockets.
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osteogenic potential of mesenchymal cells embedded in the Provisional Matrix after a 6 week healing period in augmented and non augmented extraction sockets an immunohistochemical prospective pilot study in humans
Clinical Oral Implants Research, 2012Co-Authors: Susanne Heberer, Alexander Wustlich, Hermann Lage, John J. Nelson, Katja NelsonAbstract:Purpose: The aim of the present clinical study was the evaluation of the osteogenic potential of mesenchymal cells embedded in the Provisional Matrix of non-augmented and with Bio-Oss collagen-augmented human extraction sockets after 6 weeks of healing time. Methods: Twenty-five patients with 47 extraction sites participated in the present study. After tooth removal, the extraction sockets were augmented with Bio-Oss collagen or not augmented. At implant placement, bone biopsies of the extraction sockets were obtained. The immunohistochemical analysis of the osteogenic potential of the mesenchymal cells in the Provisional Matrix was performed using three monoclonal antibodies: core-binding factor α1 (Cbfa1)/runt-related protein (Runx)2, osteonectin (OSN/secreted protein acidic and rich in cyst [SPARC]) and osteocalcin (OC). The statistical analysis was performed using two-factorial analysis for repeated measures, Mann–Whitney U-test and Spearman's rank-order correlation coefficient. Results: Of 47 extraction sockets examined, 17 sockets demonstrated an almost complete ossification. Hence, the Provisional Matrix of the 30 remaining extraction sockets (21 non-augmented, 9 augmented) was immunohistochemically investigated. No evidence of acute or chronic inflammation was noted in any of the specimens. In the Provisional Matrix of the non-grafted socket, the median amount of Cbfa1/Runx2-positive cells was 72.3%, of OSN (SPARC) 66.9% and of OC 23.4%, whereas in the grafted sockets the median rate of immunopositive cells staining with Cbfa1/Runx2 was 73.3%, of OSN (SPARC) 61.4% and of OC 20.1%. There was no significant difference in the proportion of positive cells expressed by Cbfa1/Runx2, OSN/SPARC and OC between the grafted and non-grafted socket. Furthermore, the cell density did not correlate to the quantity of stained cells independent of the used proteins. Discussion: After a 6-week healing period, the Provisional Matrix was demonstrated to have a high proportion of cells displaying a maturation of mature osteoprogenitor cells to osteoblasts. The grafting procedure did not influence the quantity of osteogenic cells in the extraction socket. To cite this article: Heberer S, Wustlich A, Lage H, Nelson JJ, Nelson K. Osteogenic potential of mesenchymal cells embedded in the Provisional Matrix after a 6-week healing period in augmented and non-augmented extraction sockets: an immunohistochemical prospective pilot study in humans. Clin. Oral Impl. Res. 23, 2012; 19–27. doi: 10.1111/j.1600-0501.2010.02148.x
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Osteogenic potential of mesenchymal cells embedded in the Provisional Matrix after a 6‐week healing period in augmented and non‐augmented extraction sockets: an immunohistochemical prospective pilot study in humans
Clinical oral implants research, 2011Co-Authors: Susanne Heberer, Alexander Wustlich, Hermann Lage, John J. Nelson, Katja NelsonAbstract:Purpose: The aim of the present clinical study was the evaluation of the osteogenic potential of mesenchymal cells embedded in the Provisional Matrix of non-augmented and with Bio-Oss collagen-augmented human extraction sockets after 6 weeks of healing time. Methods: Twenty-five patients with 47 extraction sites participated in the present study. After tooth removal, the extraction sockets were augmented with Bio-Oss collagen or not augmented. At implant placement, bone biopsies of the extraction sockets were obtained. The immunohistochemical analysis of the osteogenic potential of the mesenchymal cells in the Provisional Matrix was performed using three monoclonal antibodies: core-binding factor α1 (Cbfa1)/runt-related protein (Runx)2, osteonectin (OSN/secreted protein acidic and rich in cyst [SPARC]) and osteocalcin (OC). The statistical analysis was performed using two-factorial analysis for repeated measures, Mann–Whitney U-test and Spearman's rank-order correlation coefficient. Results: Of 47 extraction sockets examined, 17 sockets demonstrated an almost complete ossification. Hence, the Provisional Matrix of the 30 remaining extraction sockets (21 non-augmented, 9 augmented) was immunohistochemically investigated. No evidence of acute or chronic inflammation was noted in any of the specimens. In the Provisional Matrix of the non-grafted socket, the median amount of Cbfa1/Runx2-positive cells was 72.3%, of OSN (SPARC) 66.9% and of OC 23.4%, whereas in the grafted sockets the median rate of immunopositive cells staining with Cbfa1/Runx2 was 73.3%, of OSN (SPARC) 61.4% and of OC 20.1%. There was no significant difference in the proportion of positive cells expressed by Cbfa1/Runx2, OSN/SPARC and OC between the grafted and non-grafted socket. Furthermore, the cell density did not correlate to the quantity of stained cells independent of the used proteins. Discussion: After a 6-week healing period, the Provisional Matrix was demonstrated to have a high proportion of cells displaying a maturation of mature osteoprogenitor cells to osteoblasts. The grafting procedure did not influence the quantity of osteogenic cells in the extraction socket. To cite this article: Heberer S, Wustlich A, Lage H, Nelson JJ, Nelson K. Osteogenic potential of mesenchymal cells embedded in the Provisional Matrix after a 6-week healing period in augmented and non-augmented extraction sockets: an immunohistochemical prospective pilot study in humans. Clin. Oral Impl. Res. 23, 2012; 19–27. doi: 10.1111/j.1600-0501.2010.02148.x
Daniele Botticelli - One of the best experts on this subject based on the ideXlab platform.
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Sequential morphometric evaluation at UnicCa® and SLActive® implant surfaces. An experimental study in the dog.
Clinical oral implants research, 2016Co-Authors: Vittorio Favero, Niklaus P. Lang, Riccardo Favero, Luiz Antonio Salata, Evandro Carneiro Martins Neto, Daniele BotticelliAbstract:To study sequential osseointegration around implants with nano-technologically modified surfaces at different periods of healing. After 3 months, two different implant systems with different nano-technologically modified surfaces were randomly installed in the edentulous molar regions of the mandible of 12 dogs. One surface was acid-etched surface, and subsequently modified with calcium ions (UnicCa® ), while the other was a hydrophilic sandblasted with large grit and acid-etched (SLActive® ) surface. The implants were fully submerged, and biopsies were obtained representing the healing after 1, 2, 4 and 8 weeks (n = 6 per period). A morphometric evaluation of densities of new soft tissues (Provisional Matrix and immature bone marrow), new and old bone, mature bone marrow, vessels and other tissues (bone debris/particles and clot) was performed in the spongiosa compartment of the sites of implantation. After 1 week of healing, the soft tissues, mainly composed of Provisional Matrix, were present at 41.5 ± 23.9% and 30.1 ± 20.0% at the UnicCa® and SLActive surfaces, respectively. These percentages were >40% at both surfaces after 2 weeks of healing, presenting greater amount of immature bone marrow. Subsequently, these percentages decreased up to disappear after 8 weeks of healing. New bone increased progressively between 1 and 8 weeks of healing from 8.2 ± 3.0% to 77.1 ± 6.4% and from 6.8 ± 2.8% to 67.9 ± 6.8% at the UnicCa® and SLActive® , respectively. Old bone decreased progressively over time. The patterns of healing at highly hydrophilic surfaces occurred through the early formation of a Provisional Matrix followed by the formation of new bone and marrow at various stages of maturation. The healing was similar to those described in different animal models, anatomical sites and surgical procedures. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Sequential morphometric evaluation at UnicCa(®) and DCD(®) implant surfaces. An experimental study in the dog
Clinical oral implants research, 2016Co-Authors: Vittorio Favero, Niklaus P. Lang, Riccardo Favero, Antonio Azoubel Antunes, Luiz Antonio Salata, Daniele BotticelliAbstract:AIM: To study sequential osseointegration around implants with nano-technologically modified surfaces at different periods of healing. MATERIALS AND METHODS: After 3 months, two different implant systems with different nano-technologically modified surfaces were randomly installed in the edentulous molar regions of the mandible of 12 dogs. One surface was acid-etched surface, and subsequently modified with calcium ions (UnicCa(®) ), while the other was a hydrophilic sandblasted with large grit and acid-etched (SLActive(®) ) surface. The implants were fully submerged, and biopsies were obtained representing the healing after 1, 2, 4 and 8 weeks (n = 6 per period). A morphometric evaluation of densities of new soft tissues (Provisional Matrix and immature bone marrow), new and old bone, mature bone marrow, vessels and other tissues (bone debris/particles and clot) was performed in the spongiosa compartment of the sites of implantation. RESULTS: After 1 week of healing, the soft tissues, mainly composed of Provisional Matrix, were present at 41.5 ± 23.9% and 30.1 ± 20.0% at the UnicCa(®) and SLActive surfaces, respectively. These percentages were >40% at both surfaces after 2 weeks of healing, presenting greater amount of immature bone marrow. Subsequently, these percentages decreased up to disappear after 8 weeks of healing. New bone increased progressively between 1 and 8 weeks of healing from 8.2 ± 3.0% to 77.1 ± 6.4% and from 6.8 ± 2.8% to 67.9 ± 6.8% at the UnicCa(®) and SLActive(®) , respectively. Old bone decreased progressively over time. CONCLUSIONS: The patterns of healing at highly hydrophilic surfaces occurred through the early formation of a Provisional Matrix followed by the formation of new bone and marrow at various stages of maturation. The healing was similar to those described in different animal models, anatomical sites and surgical procedures.
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Peri-implant tissues morphometry at SLActive surfaces. An experimental study in the dog.
Clinical oral implants research, 2015Co-Authors: Vittorio Favero, Niklaus P. Lang, Riccardo Favero, Fabio Rossi, Davide Baffone, Daniele BotticelliAbstract:Objective The objective was to study tissue components around implants with highly hydrophilic surfaces during early healing. Materials and methods In 12 Labrador dogs, the second and third mandibular premolars were extracted bilaterally. After 3 months of healing, full-thickness flaps were elevated in the edentulous region of one side of the mandible. An implant was installed, and the flaps were sutured to allow a non-submerged healing. The timing of the implant installations in the other side of the mandible until sacrifices were performed in such a way to collect biopsies representing healing after 4, 7, 15, and 60 days. An n = 6 was achieved for each healing period. Paraffin sections were obtained for morphometric analyses. Results Provisional Matrix with a percentage of 32.9 ± 16.7% was found already after 4 days. This percentage became 37.3 ± 8.5%, 24.3 ± 9.1%, and 1.6 ± 1.7 after 7, 15, and 60 days, respectively. New bone was found after 7 days of healing, at a percentage of 26.2 ± 3.2%. This proportion increased to 36.0 ± 9.6% and 50.4 ± 8.3% after 15 and 60 days, respectively. Marrow spaces free from a blood clot, inflammatory cells, and Provisional Matrix represented a low proportion of the tissues after 4 days (1.6 ± 2.4%). This proportion increased over time to 9.2 ± 6.4%, 20.3 ± 12.9%, and 37.9 ± 9.6%, respectively. The percentage of old bone was noted in a similar percentage (~8%) up to 15 days. The percentage decreased to ~5% at 60-day of observation. Conclusion The tissue changes observed during the healing were similar to those from historic controls studying healing in a chamber adjacent to implants. Hence, the characteristics of the implant surfaces may not be reflected in the tissue composition adjacent to the implant but rather affect the adhesion of tissue onto the implant surfaces.
